L-Citrulline

Quick Overview

L-citrulline 250 mg powder

L-citrulline is a non-essential amino acid synthesized from the breakdown of L-ornithine and L-arginine during the urea cycle. L-citrulline is not an amino acid coded for by DNA, and in that sense, is not involved in protein synthesis. However, L-citrulline is a central part of the urea cycle, which allows the body to dispose of excess nitrogen. L-citrulline is frequently consumed by athletes as part of their workout supplement program.

L-citrulline is one of the three amino acids in the urea cycle (the other two being L-arginine and L-ornithine). The urea cycle converts a toxic compound called ammonia into urea, which is then eliminated from the body through urine. After ingestion, L-citrulline is converted to L-arginine by the kidneys and is released into the bloodstream by the kidneys so that it is available to the whole body. L-arginine, a precursor to nitric oxide. Nitric oxide synthase produces nitric oxide from L-arginine. Nitric oxide plays a crucial role in the immune system and heart and blood vessel health. Many of the benefits of L-citrulline are due to L-arginine and nitric oxide. L-Citrulline is also formed as a by-product in the production of nitric oxide from arginine. It can be recycled back to arginine in what is known as the citrulline-NO cycle.

Dosage for L-CitrullineL-citrulline supplements can be taken in different dosages, depending on what they are being used for.For treating erectile dysfunction,1,500 mg per day was proven to be an effective dosageTo reduce fatigue and increase workout capacity, 2,400 mg per day was an effective dosageFor heart failure, a dosage of 3,000 mg per day was effectiveTo reduce blood pressure, 3,000 mg per day was effective in reducing blood pressureL-citrulline can also be supplemented in the form of citrulline malate. Doses of 6 to 8 g of citrulline malate have been used to increase athletic performance and workout capacity

Details

User ExperiencesMany people report that L-citrulline supplements are very effective at increasing energy levels and exercise capacity when taken pre-workout. Many people also report that L-citrulline is very helpful in regulating their blood pressure and maintaining their overall health. While most people were happy with the supplement, others reported that it did not work for them or that it caused them to feel sick.

Benefits of L-Citrulline

1) L-Citrulline Decreases Fatigue and Muscle SorenessA study of 18 men with fatigue found that L-citrulline reduced fatigue and increased ATP levels. Every man reported a reduction in fatigue after exercise. L-Citrulline also increased the production of creatine phosphate, which is a form of energy reserves in the muscles [R].

Another study (DB-RCT) of 41 men showed that citrulline malate reduced fatigue. Those receiving citrulline were able to do more reps per set of bench presses and experienced less soreness after exercise [R].

A study (DB-RCT) on 22 men found that L-citrulline increased cycling speed and reduced muscle fatigue compared to placebo [R].

A randomized clinical trial on 30 heart failure patients showed that citrulline may increase exercise capacity. Those who were given l-citrulline were able to exercise on a treadmill for longer [R]. As previously mentioned, healthy men who were given L-citrulline also saw an increase in exercise capacity, either by being able to do more bench presses or cycle faster [R, R].

3) L-Citrulline Reduces Erectile DysfunctionA single-blind study of 24 men over the age of 55 showed that L-citrulline improves erectile dysfunction (ED) and increases the hardness of erections. Some men reported having more sex after treatment and being more satisfied [R].

L-citrulline supplements improved erectile dysfunction and reduced dysfunction caused by low blood pressure in rats. This is likely due to an increase in nitric oxide [R, R].

A study of 10 children with a mitochondrial disorder found that L-citrulline supplements effectively increased nitric oxide levels due to an increase in arginine [R].

5) L-Citrulline May Increase Blood Flow

A combination of L-citrulline and L-arginine supplements increased blood flow in the ears of rabbits [R]. A study of 10 healthy young men found that nitric oxide plays an important role in regulating blood flow [R]. Other studies, one being a DB-RCT, found that L-citrulline effectively increases nitric oxide [R, R]. This suggests that L-citrulline may increase blood flow.

6) L-Citrulline Decreases Blood Pressure

A study (DB-RCT) on 12 healthy young men showed that L-citrulline decreased systolic blood pressure and increased nitric oxide levels. Nitric oxide causes blood vessels to dilate, which lowers blood pressure [R]. Another study of 12 healthy young men found that L-citrulline decreases both systolic and diastolic blood pressure [R].

7) L-Citrulline Improves Heart Function

A study of 30 patients with heart failure found that l-citrulline increased the volume of blood pumped out of the right ventricle of the heart and lowered blood pressure in the pulmonary artery [R, R]. A study of 35 patients revealed that L-citrulline improved the function of both the right and left ventricles as well as endothelial function [R].

8) L-Citrulline May Increase Growth HormoneA study (DB-RCT) on 17 cyclists revealed that L-citrulline increased growth hormone levels after exercise, but not at rest. This is most likely due to an increase in arginine levels. Arginine blocks the release of growth hormone inhibiting hormone [R].

10) L-Citrulline May Help Treat Sickle Cell AnemiaA study of 5 African-American patients with sickle cell anemia showed that L-citrulline supplementation may be a useful treatment for the disease. The patients treated with L-citrulline had reduced symptoms of the disease along with a decrease in white blood cells to normal counts [R].

11) L-Citrulline Helps Treat Urea Cycle DisordersUrea cycle disorders are genetic disorders that impair the elimination of ammonia from the body [R]. L-Citrulline supplements can help treat urea cycle disorders by removing ammonia from the bloodstream and preventing a build-up of it [R].

Side Effects of L-CitrullineThe most common side effect is stomach upset [R, R].